Fire alarm and detector



Filed April 8.

H FRADAS FIRE ALARM AND DETECTOR Oct. 11, 1927.

Degree 6146(- INVENTOR, #9727 PradaS;

MW ATTORNE Patented Oct. 11, 1927.

UNITED 'ls'ra'rss tenseearrnr oFFicE.

HENRY PRADAS, OFLOS ANGELES, CALIFORNIA, ASSIGNOE OF ONE-THIRD TO MARTIN KROEGER AND ONE-THIRD TO LOUIS CABRILLO, BOTH 0]? LOS ANGELES, CALI- FQRNIA.

Application filed April 8,

This invention relates to signal apparatus and more especially to temperature'controlled means for completing an electric circuit associated with any desired audible, visible or other apparatus for effecting the alarm.

An object of the invention is to provide means operative by the expansion of air which is heated in the event of the increment of heat above a predetermined degree.

Another object is to provide an apparatus of simple, inexpensive form, and which, when once set for operation at a predetermined degree of temperature, will thereafter be in constant readiness for action, and

whose parts are not liableto be readily dis-X adjusted or placed out of order except by intent, unless by complete destruction.

Additional objects are to provide a thermosensitive, automatically acting device which can be easily regulated to function reliably at a rise in temperature above the desired high degree in any given place of use or installation; to provide a device which can be tested from time to time without making any adjustments of parts, and without resulting in injury or destruction to the instrument or any of its elements; to provide a device which has no acids and no low point fusing media as cont-rolling agents which are destroyed at each completion of its designed operation; and therefore a broad object is to provide adevice which will operate to give a continuous signal until the temperature falls to the predetermined point, or until the signal is switched off, or the apparatus is made inoperative by fire after the signal has been effected by the device.

Other objects and advantages will be made manifest in the following specification of apparatus embodying one form of the invention; it being understood that modifications, variations and adaptations may be resorted to within the spirit and scope of the invention as here claimed.

Figure 1 is a vertical section of the device.

Figure 2 is a cross-section through the air cells or tubes.

Figure 3 is a view showing one adaptation of the invention in a signal system.

The circuit closing control is here shown as including a series'of air tubes 2 whose tops are closed by a crown or top plate 3 from which the tubes extend down in parallel FIRE ALARM AND DETECTOR.

1926. Serial No. 100,569.

relation to a manifold or base 4 having holes 5 for the ends of the tubes 2. These open at the bottom immediately over a thin diaphragm 6 which is secured at its margin to the margin of the manifold t beyond the out lets of the air tubes so that the area of the diaphragm is subjected to pressure of air expanding from any one or more of the tubes.

Since the diaphragm lies close to the face ofthe manifold 4 it willbe seen that but a very slight change in temperaturewill be sufiicient to cause expansion of air in the tubes and the expanding air acts instantly on the diaphragm so that this will be bulged outward. This action is utilized to close an electric circuit.

Below the bottom of the diaphragm is an adjustable screw 10, preferably having a platinum contact terminal 11 to engage an opposed part of the diaphragm, which is preferably of thin copper. The screw 10 is mounted in a cross-bar l2 suitably attached to the manifold 4.

A margin ring 13 is here shown as secured to rods 14; passing up through'the diaphragm and manifold and to the crown 3. The bar 12 is insulated from the other parts and from it leads a conductor 17. From the manifold leads a conductor 18. These conductors lead to any desired signal apparatus as bells B, which may be at any desired station or location at which the sigout consequence but when the temperaturereaohes a given point, determined by the screw spacing, the expanded air will force the diaphragm, or a contact piece 19, against the screw tip. Thereupon a circuit will be completed and maintained until temperature falls, or circuit is. broken, or the instrument is demolished.

While the diaphragm is herein shown and described as at the bottom of the expansion chamber of the device this is to be under stood as merely relative and not a term of limitation, since diaphragm means may form seals at top, bottom, sides or ends of the sealed air space within device. The device may be placed in any desired position and the innumerable uses of the detector need hardly to be catalogued, but in Fig. 3

it is shown as installed between floor and ceiling space, Where it will be effective to give an alarm when a predetermined temperature is reached.

What is claimed is: 7

An automatic lire alarm and detector co1nprising an imperl'orate head and apertorate manifold in spaced relation, a group of parallel thin metal tubes 'Whose upper ends are seated air tight on the bottom face of the head and hose open lower ends lie in the apertures of the manifold,a thin diaphragm lying close over the mouth of the tubes and below the manifold and forming a distensible circuit closer operative by slight ex- 1 PWl i -B of air 4 mm nyef the-w eat clamp ring below ,the diaphragm, a set 0 f clamp IOCS passing through the ring, the draphragm and the manifold and engaging in HENRY PRA-DAS; 

